Abstract

ROCA, Antonio et al. Decomposition and Cyanidation Kinetics of the Argentian Ammonium Jarosite in NaOH Media. J. Mex. Chem. Soc [online]. 2007, vol.51, n.2, pp.47-54. ISSN 1870-249X.

In this work, the synthesis, characterization, reactivity in NaOH media and the cyanidation of the ammonium jarosite are approached. The jarosite was synthesized and characterized by several analytical techniques; the granulometric analysis was also performed. The synthesis results show that the material consists of a solid ammonium-hydroniumjarosite-argentojarosite solution of an appoximate [(NH_4(0.95) Ag_0.025 H₃0 _0.025)Fe_2.66(SO₄)(OH)₆] formula. This jarositic compounds synthesis, along with the mechanical agitation system with seed recycling, has a notable effect on the spheroidization degree and on the particles growth degree, reaching the highest particle sizes of the 44-37µm ( > 61% ) kind. The decomposition and cyanidation curves show an induction period, a progressive conversion period and a stabilization zone. The SEM-EDS analysis shows an unreacting jarosite core in the progressive conversion period, as well as a gel layer, through which the sulphate ions easily diffuse towards the solution. The alkaline decomposition and the ammonium jarosite cyanidation is a process of two serial stages: A slow alkaline decomposition stage followed by an instant silver complexation stage.

Keywords : Ammonium jarosite; cyanidarion; granulometric analysis; descompositon.

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